Marks 5 speed for the Patrol

[Peter60]

MARKS 5 SPEED – Rebuild AUSTRALIA

I recently had my Marks 5 speed rebuilt by my mechanic. This guy is a retired mechanic/machinist/engineer. He has a wealth of knowledge about all things mechanical.

The problem symptom was that 5th gear seemed ‘loose’. In pulling it apart it was discovered that the 5th gear cog has become loose on the main shaft. The 5th gear was stripped where it engaged on the shaft. The shaft spline was itself stripped.

IMG_1061.jpg

I tried to locate a replacement main shaft. After much investigation it looked like the gearbox internals matched the Nissan MQ Patrol (or as it is often referred to as the 160 series). Other possibilities were the Nissan Cabstar. It was difficult to find references on-line but I did find an on-line parts diagram of the gearbox for the 160 Series.

https://nissan-europe.epc-data.com/patr ... train/322/

However, as I found out, there are 5 different main shafts for the 160 series. All were too long. So it looks like the Marks main shaft was a custom cutdown version of one of the shafts.

I ended up sending the shaft and a spare 5th gear cog to Sydney to the Gearbox Factory. They rebuilt the shaft and re-cut the groves. When returned it looks as good as new.

My mechanic then rebuilt the gearbox.

I was able to source synchro (baulk) rings from amayama.com and bearings sourced from the local bearing shop.

Part No:
Baulk rings N3260786402 – you need two
Baulk Rings N32604T8000 – you need two
The above nos are a little different that in the on-line reference
Bearings
30305JR Koyo
30306JR Koyo
6307NRC3 Nachi
6308NRC3 Nachi

I don’t know where the bearings went as they were purchased and installed by my mechanic.
Other needle bearings were reviewed and replaced if necessary.

The reason 5th gear came loose on the main shaft was that it was held in place by a ‘collar’ and a circlip. The circlip was fairly thick but had broken in several pieces. My mechanic wasn’t happy with that arrangement and ended up building something else to hold 5th gear in place (again I really don’t know what). He then put a small shim on the transfer case shaft so it would butt up more closely to the main shaft and ‘reduce the sideway movement’ of the 5th gear.

I need to use a .5mm (half a mm) gasket paper between the gearbox and the transfer case to make sure things fit snuggly.

Currently the gearbox is sitting on my workshop floor waiting till I have time to install it.

I did contact Marks 4WD for information and they sent me these two documents.

MFK092RK.pdf

MFK092.pdf

And finally for information the Marks gearbox need a special shaft in the transfer case. So if you find a Marks gearbox be sure you get the transfer case as well

IMG_1619.jpg

[RiverPatrol]

Excellent detailed information for those rare Marks 5 speeds, thanks for sharing.